Effect Measure is a forum for progressive public health discussion and argument as well as a source of public health information from around the web that interests the Editor(s)

Wednesday, September 07, 2005

E. coli in New Orleans flood water

The Big Headline on CNN says that E. coli has been found in New Orleans floodwaters. Duh. I guess now that even CDC has contradicted Secretary Leavitt's statement that cholera is a problem, a new deadly organism was needed. Ergo, E. coli.

Some E. coli is a problem, but most isn't. If it were, we'd all be dead, since the organism constitutes about 4% of our normal gut flora. True, there are some special strains that carry genetic sequences that either make toxins or confer the ability to invade the gut wall, but for the most part the significance of the presence of "coliform organisms" is that they signal the potential contamination of water or food with the feces of warmblooded animals and hence with other pathogens. E. coli is thus an "indicator organism." Moreover, what is often called "E. coli" is not even that, but rather a whole group of organisms that are easily tested for ("total coliforms" or "fecal coliforms" being the most common). These organisms are commonly and normally found in storm runoff. They are killed by primary disinfection in a water treatment plant, so their appearance in a drinking water supply is evidence that something has gone amiss, usually resulting in a "boil water order" until it can be corrected. This is just by way of making clear things that are anything but clear from news reports.

But it is also abundantly clear that there is a gigantic problem with the sanitary quality of these flood waters. The environmental temperatures in the nineties promote the growth of human pathogens, which like to grow at temperatures similar to those of the human body. In addition, sewage contamination of the water means that it almost certainly contains enteric viruses that cause diarrhea, nausea and vomiting. So it is quite likely that there will be many cases of gastrointestinal disease. In addition, there is likely infectious hepatitis in the mix (hepatitis A). Viral hepatitis is often a mild or even inapparent self-limiting disease, but in a significant percentage of cases it can be extremely debilitating or even fulminant and fatal. We won't see it for a while, because it has a relatively long incubation period of two to six weeks. It is relatively easily spread in crowded conditions, which means that if evacuees will be remaining in crowded shelters much longer, vaccination should be undertaken in all these facilities as soon as possible. All relief workers should also be vaccinated.

There are a number of other conditions related to bacteria-laden water that are also important, although not because they will cause epidemics. Injury may be the number one health problem, so wound infections need to be promptly and aggressively attended to and tetanus immunization administered for puncture wounds. Most skin infections will be self-limiting and easily treated, but some are of special importance in this geographic area, among them Vibrio vulnificus (described in new reports as a "cousin" of cholera but clinically quite different). V. vulnificus might have already claimed a number of victims in the Gulf.

As we and others have pointed out in other posts, the chemical contamination of the water is important in the clean-up and rebuilding effort. In addition, if this water is pumped back into the Lake it will almost certainly cause massive fish kills. A portable primary treatment plant should at least be considered.

But that kind of foresight is asking quite a lot from a government what was totally unprepared for the basic needs of the moment, let alone those that will become basic needs shortly as a result of the improvised and poorly thought out responses. Quite a lot, but not too much to ask.